This invention relates to a probe for ultrasonic-echo planigraphic imaging apparatus used when a puncturing cannula is inserted into the predetermined portion of a living human body as in biopsy.
In recent years, a blood vessel-imaging method is applied as important means for discovering morbid changes in the cerebrum, heart, abdominal organs and limbs. This method comprises the steps of inserting a puncturing cannula into the pancreatic duct or cystic duct of the above-mentioned sections of a human body to pour a contrasting mediums thereinto and carrying out the X-ray photography of the predetermined portions of said sections. Another important examining method is to aspirate a tissue of the organs of a human body such as a liver, kidney or tumor by means of a puncturing cannula.
In this case, it is very important to determine the exact position of that part of the organs or blood vessels which is to be pierced by a puncturing cannula in order to avoid the biopsy of an unnecessary tissue of the organs or the flow of contrast medium into the wrong tissue. Further, it will offer great advantage if the behavior of a puncturing cannula can be traced in real time which occurs during a period extending from a point of time at which the cannula begins to be inserted to a point of time at which said cannula reaches the tissue of the predetermined organ.
A planigraphic imaging apparatus utilizing ultrasonic waves is already used for the above-mentioned object. This ultrasonic-echo planigraphic imaging apparatus comprises a probe consisting of a plurality of electro-acoustic transducer elements which are linearly arranged at least in that portion of said probe which contacts the human body and whose adjacent ones are simultaneously operated.
The sectional plane of that portion of the human body which is to be inserted by the puncturing cannula is progressively scanned by ultrasonic beams supplied from the above-mentioned transducer elements. The resultant planigraphic image is indicated on the CRT of a display device.
A probe used to discover the position of the predetermined portion of a human body before the X-ray photography thereof has to be removed at the time of photography in order to prevent an unnecessary image of the probe itself from being indicated on the CRT of the display device.
There will now be described by reference to FIGS. 1a and 1b a conventional probe. The probe 1 comprises a support 4 provided with a plurality of transducer elements 3 arranged at least in one row on that side 2 of the probe 1 which made to contact a human body; and a guide slit 5 which extends lengthwise of the support 4 over the linearly arranged transducer elements 3 to guide the insertion of a puncturing cannula 6. The guide slit 5 has a V-shaped cross section which is gradually broadened from the human body-contacting side 2 of the support 4 toward the upper opposite side thereof. Accordingly, the puncturing cannula 6 is conducted from above the guide slit 5 into the predetermined portion of a human body. Where the puncturing cannula 6 reaches the prescribed position, the probe has to be removed from the human body for the reason previously given. During the removal, the conventional probe 3 provided with the above-mentioned guide-slit 5 unavoidably touches the puncturing cannula 6 already inserted into the human body. As a result, the direction in which the puncturing cannula 6 is inserted would probably be changed to injure an undesired portion of the human body. Further, once the puncturing cannula 6 is inserted through the guide slit 5 of the probe 1, an operator cannot freely change the direction in which the puncturing cannula 6 is to be inserted. Moreover, unless the operator applies a uniform force to the cannula 6, then there arises the undesired possibility of the cannula 6 being inserted in the wrong direction. With the conventional probe 1, therefore, high skill has been demanded for the accurate insertion of the cannula 6.